Two-zone pulverizing apparatus



July 9, 1929. F. H. DANIELS TWO-ZONE PULVERIZING APPARATUS Filed April12, 192'? P1251) H DANIELS ATTORNEY Patented July 9, 1929.

v UNITED STATES PATENT OFFICE.

FRED H. DANIELS, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO RILEY STOKERCORPORATION, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSA-CHUSETTS.

TWO-ZONE PULVERIZING APPARATUS.

Application filed April 12,

This invention relates to a pulverizing apparatus, and more particularlyto a machine having two pulverizing zones, one for preliminarilycrushing the coarse material, and the other for finely grinding thesame.

In one form of pulverizing apparatus as heretofore constructed, thepreliminary crushing operation has been efiected largely by impact,revolving swing hammers mounted within an annular perforated grid beingutilized for this purpose. These prior constructions have all beensubject to certain inherent disadvantages. For example, it has beenfound in practice that the openings in this grid tend to become pluggedand obstructed, particularly when Wet materlal is being treated. therebyreducing the capacitv and etliciencv of the apparatus. Moreovcr. theWear on the hammers and perforated grid is excessive in certaininstances, and it is particularly severe if hard foreign bodies enterthe machine with the coarse material and must be worn away untilsufticiently small to pass through the perforations in the grid. I havediscovered that for certain purposes a more satisfactory operation isobtained by providing ad acent to the path of the hammers an accumulatedmass of the material being pulverized, so that the incoming material iscrushed by the hammers against this accumulation. This construction hasa further advantage in that it eliminates practically all possibility ofdamage to parts of the machine from hard foreign bodies. for if suchbodies enter with the coarse material they are innn diately embedded inthe comparatively soft niass outside the hammer path.

It is accordingly one object of my invention to provide a pulverizingapparatus of this type in which the preliminary crushing operation iseffected largely by attrition as distinguished from impact and in whichliability of damage from foreign bodies or plugging by Wet material isreduced tov the minimum.

A further object of my invention is to provide an improved means forintroducing air into the preliminary crushing zone, so as to transportmaterial to the second zone as fast as it is sufficiently crushed, andto prevent all possibility of wet material adhering to the apparatus atundesired points.

Pulverizing machines have been construct- 1927. Serial No. 133,181.

ed in which a rotor-disk, mounted to rotate about a horizontal axis, isprovided to separate the pulverizing chamber into the two pulverizingzones. In such machines, coarse material thrown off by the preliminarybreakers tends to accumulate in the bottom of the pulverizing chamberbeneath the rotor disk. If the rotor rubs against this pile of material,excessive wear and friction on the rotor disk is caused thereby.Moreover this rubbing acts as a brake on the machine, overloading thedriving motor and limiting the capacity of the pulverizer.

It is accordingly a further object of my invention to provide apulverizing apparatus of this type in which the rotor Will be free torotate without contact with an accumulated mass: of material.

With these and other objects in view as will be apparent to thoseskilled in the art, my invention resides in thecombination of parts setforth in the specification and covered oy the claims appended hereto.

In accordance with my invention, I provide a pulverizing apparatushaving two pulverizing zones connected by a peripheral passage so thatthe material preliminarily crushed in one chamber is fed to theperipheral outer portion of the second chamber whence it is caused topass inwardly toward a centrally disposed outlet. In my preferredconstruction. the two grinding zones may be formed by means of adisk-shaped rotor arranged centrally of the casing and spaced adjacentto its periphery from the casing wall so as to provide a communicatingpassage around its edge. A set of revolving heaters are so arranged inthe second zone that material fed thereto is obliged to pass against theaction of centrifugal force set up by the boaters towards a centrallydisposed outlet and thus be subjected to a fine pulverization. In thefirst zone, I prefer to utilize revolving hammers to crush the materialpreliminarily, and to so arrange these hammers that they may sweep overan accumulated mass of the ma: terial being treated, the incomingmaterial being crushed thereagainst by attrition, and hard foreignbodies being embedded therein. Suitable provision may be made forremoving these foreign bodies at the convenience of the operator. Thehammers are prefer-- ably pivotally mounted, so as to swing freely andyield in case a particularly hard foreign body is met. Since thematerial may lodge to some extent in the bottom of this preliminarycrushing zone and frictionally drag against the rotor, it is preferredin such instances to provide a partition which separates the rotor fromthe space within the first zone thereby holding the coarse material awayfrom its sides and permitting it to rotate freely. Moreover, it isdesired that air be admitted to this casing in order that the materialmay be readily transported therefrom as soon as it is crushed, and whilethe air may be introduced with the coarse material, I preferably provideinlet openings adjacent the periphery of the preliminary crushing zone,and these are so arranged that the amount of air introduced may bevaried at will. A fan serves to transport the material from the casingand to move it to a desired locality such as the burner of a furnace iffuel is the material being pulverized.

Referring to the drawings illustrating one embodiment of my invention,and in which like reference numerals indicate like parts:

Fig.1 is a vertical section substantially through the center of theapparatus, illustrated somewhat diagrammatically;

Fig. 2 is a section On the line 22 of Fig. 1;

Fig. 3 is a partial section on the line 33 of Fig. 1;

Fig. 4 is a partial section on the line 44 of Fig. 1; and

Fig. 5 is a perspective view of a rejector blade.

The embodiment of the invention illustrated in the drawings comprises acasing arranged to form a pulvcrizing chamber and a casing 12 arrangedto form a fan chamber. These two chambers are connected by a passage 14which forms a centrally located outlet for the pulverized material. Asubstantially disk-shaped rotor 15 is mounted within the pulverizingchamber 10. The rotor 15 is mounted on a hub 16 which is keyed to ahorizontal shaft 18 mounted in suitable bearing in the casing, An inletopening 20 for the introduction of coarse material from the chute 21 isprovided in the casing wall on the opposite side of the rotor from theoutlet 14. A series of revoluble swinging hammers 23 are arrangedadjacent to the inlet 20 and in the path of the incoming material toinitially pulverize it. These hammers 23 are illustrated as pivotallymounted by means of bolts 25 on a flanged hub 26 which is keyed to theshaft 18. As illustrated, the hammer ends are spaced from thesurrounding casing wall, and such annular space communicates directlywith the peripheral passage which connects the two pulverizing zonesaround the disk.

In order to pulverize material finel in the second zone adjacent theoutlet, ar-

range revoluble impact members or pegs 28 which are mounted upon therotor disk 15. If desired, stationary pegs 29 may be mounted upon thecasing wall to cooperate with the revoluble pe s in pulverizing thematerial. These sets of pegs are. preferably arranged in concentriccircles, and the stationary pegs are located close to the path of therevolving pegs, as.shown clearly in Fig. 3. They may be mounted in anysuitable manner upon their supports, but the preferred form of mountingis fully disclosed in the patent to Riley, No. 1,576,472.

If desired, a set of substantiallly radial rejector arms may be mountedon the hub 16 and arranged to revolve within a beveled ring 36 whichsurrounds the outlet opening 14. These rejector arms serve to scoop outof the issuing cloud of pulverized material any coarse particles whichmay be present therein, and return them to the pulverizing elements forfurther comminution.

A suitable fan 40 is mounted on the shaft 18 within the fan chamber 12and it is arranged to draw a current of air through the machine andforce it out of a tangential outlet 41. The air may enter thepulverizing chamber with the coarse material, but in my preferredconstruction I provide a series of air openings in the wall of the firstpulverizing zone. These openings 45 are preferably arranged, asillustrated, in the upper portion of the preliminary crushing zone andon the outside vertical wall so that they may direct a stream of airacross the outer portion of the first zone and directly to the passagearound the rotor, thus assisting in transporting the material which isthrown off from the revolving swing hammers into the second pulverizingzone. It is desirable to provide means for controlling the flow of airthrough these openings 45. Any suitable device may be arranged for thispurpose, but I prefer to provide a manifold 47 which covers the openingsand is provided with an adjustable butterfly damper 48. If desired,heated air may be drawn through the manifold 47 from any suitableheating device, not illustrated. The use of heated air is especiallydesirable when the material undergoing pulverization has a highpercentage of moisture therein.

In order to prevent any accumulation of coarse material beneath therotor disk 15 I provide a suitable partition wall or plate 50. In theembodiment illustrated, this plate 50 is arranged in a vertical planeclosely adjacent to the disk 15 and between the disk and-the swinghammers 23. This plate is mounted in the lower half of the casing onlyand in the preferred construction it extends substantially to thehorizontal center line of the machine. This plate 50 may be attached tothe casing wall 10 in any suitable manner, as by means of small clipangles 51.

It is apparent from an inspection of the drawing, that this constructionprovides a space beneath the swing hammers 23 in which coarse materialmay accumulate without contact with the rotating disk. Any hard foreignbodies which enter the machine will immediately be embedded in thisaccumulation. If desired, a suitable slide 55 (Fig. 1) may be arrangedto permit access to the' accumulated mass of material in the bottom ofthe machine.

The operation of the apparatus will now be apparent from the abovedisclosure. The shaft 18 is rotated by any suitable source of power, andcoarse material is delivered to the chute 21 by any suitable feedingdevice. The material is crushed by the attrition action of the revolvingswing hammers 23 which sweep over the mass of coarse materialaccumulated in the space beneath them. Any hard foreign bodies which mayenter the machine are immediately embedded in this mass without causingexcessive wear on the hammers. the casing is clear, and the crushedmaterial will be thrown upwardly and caused to pass into the second zoneat the top of the apparatus. Air is drawn into the machine through theopenings 45 by the action of the fan 40 and this air current carries thematerial from the first zone around the rotor disk into the secondpulverizing zone. The air from the inlets 45 passes as jets across theperipheral wall of the casing and tends to keep it clear of deposits ofdamp material hurled by the hammers against the wall. It is particularlydesirable to preheat this air so that the heat will evaporate moisturefrom the fuel that tends to accumulate on the wall, thereby serving toprevent the fuel sticking to any large extent. This air may be suitablypreheated, such as by connecting the inlet pipe to a passage withinhollow walls of the furnace, and the temperature may be regulated asdesired.

In the second zone, material is uniformly and finely pulverized by theaction of the revolving impact pegs 28 and the stationary pegs 29. Finematerial passes inwardly against centrifugal force towards the centrallylocated outlet 14 and thence into the fan casing 12 and is forced out ofthe outlet opening 41. Any coarse material which reaches therejectorarms 35 is immediately returned to the pegs for further pulverization.There are no small openings through which the material has to pass andfor this reason all danger of plugging with wet material is eliminated.

It will also be observed that the pegs 28 and 29 are relatively largeand that but one row of each set of pegs is illustrated, although morethan one row of either or both sets may be employed to advantage in cer-Only the upper portion of tain cases. The pegs 28 are short so that awide clearance is provided between their ends and the casing linerplate. This leaves aspace for fine material to pass directly to theoutlet without contact with the revolving beaters. The stationary pegs29 are found to decrease the fineness of the H1- terial, apparentlypreventing it from remaining in contact with the beater pegs 28 for anylength of time, and the degree of fineness of the produ may be adjusteddepending upon the size, location and number of the stationary pegs. Byhaving but a single row of each set of pegs, I insure a low powerconsumption, and in that case depend upon the rejector blades to returnto the grinding members such coarse particles as may get by them.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1 A pulverizing apparatus comprising a casing havmg an inlet for coarsematerial and an outlet for pulverized material, means forming twoperipherally communicating pulverizing zones adjacent to the inlet andoutlet respectively, means to retain within the first zone and preventits passing to the second zone an accumulated mass of material.revoluble members in the first zone arranged to sweep over thisaccumulated mass and crush incoming coarse material thereagainst byattrition, and revoluble impact members in the second Zone to finelypulverize material passing thereto from the first zone.

2 A pulverizing apparatus comprising a casing having an inlet and anoutlet located centrally thereof, a rotor disk mounted within the casingand arranged to form two peripherally connected pulverizing zonesadjacent the inlet and outlet respectively, a-

series of substantially radial revoluble hammers within the first zonefor preliminarily crushing coarse material by attrition against. anaccumulated mass of the material being treated, and impact membersll'lOtllltOttOI] the rotor in the second zone and arranged to finelypulverize material as it passes inwardly against centrifugal forcetowards the outlet.

3. A pulverizing apparatus comprising a casing having an inlet forcoarse material and an outlet for pulverized material, means forming twoperipherally communicating pulverizing zones adjacent the inlet andoutlet respectively, means to retain an accumulated mass of material inthe lower portion of the first zone and prevent its passing to thesecond zone, rcvoluble members in the first zone arranged to sweep overthis accumulated mass and crush coarse material thereagainst byattrition, said revolublezone so to provide a space in which materialmay be crushed ,by repeated impacts, and means in the second zone forfinely pnlverizing material.

A pulverizing apparatus comprising a 4 using, a rotor disk thereinarranged to form a pulverizing zone on each side thereof whichcommunicate adjacent to the periphery of the rotor, means in each zoneto pulverize material therein, and means preventing communicationbetween the zones adjacent to the lower portion of the rotor, wherebythe preliminarily crushed material must pass to the second zone only atthe upper portion of the casing.

5. A pulverizing apparatus comprising a casing, a rotor disk thereinarranged to form a pulverizing zone on each side thereof whichcommunicate outside the periphery of the rotor, means in the first zonefor crushing coarse material, means'in the second zone for finelygrinding material, means preventing communication between the zonesadjacent to the lower portion of the rotor, and means for introducingstreams of air into the upper portion of the first zone to assist intransporting the crushed material past the rotor and into the secondzone.

6. A pulverizing apparatus comprising a casing having an inlet and acentrally located outlet, a rotor mounted within said casing in such away as to form two pul verizing zones adjacent to the inlet and outletrespectively which communicate at the periphery of the rotor, a rotarybeater in the first zone arrangedto preliminarily crush materialdelivered through said inlet, impact members on the rotor in the secondzone to pulverize the material finely as' it passes to the centrallylocated outlet,

and means causing the preliminarily crushed material to enter the secondzone only at the upper portion of the casing adjacent to the peripheryof the rotor.

7. A pulverizing apparatus comprising a casing having an inlet and anoutlet therein, means forming two pulverizing zones which communicateonly at the top peripheral portion of the casing, revoluble means withinthe first zone for crushing material preliminarily, meansin the secondzone for pulverizing material finely, and means for in troducing airdirectly into the casing adjacent to the peripheral wall thereof so asto blow the fines directly to the second zone.

8. A pulverizing apparatus comprising a casing having an inlet and acentrally 10- cated outlet, a rotary beater arranged adjacent to theinlet to crush coarse material delivered therethrough, a rotor mountedwithin the casing between the beater and the outlet, impact members onthe rotor adjacent to the outlet for pulverizing material finely, and apartition wall in the lower part of the casing between the beater andthe rotor, Said wall being located close to the rotor and so arranged asto prevent material from accumulating against the side thereof.

9. A pulverizing apparatus comprising a casing having an inlet, arotatable substantially horizontal shaft extending into said casing,means forming an outlet for ma terial adjacent to the axis of saidshaft, a partition wall within the casing and beneath the shaft, arotary beater mounted on the shaft on the opposite side of the partitionwall from the outlet, a rotor mounted on the shaft on the same side ofthe partition wall as the outlet, and impact members on said rotor topulverize material finely.

10. A pulverizing apparatus comprising a casing having an inlet and acentrally located outlet, a horizontal shaft rotatably mounted withinthe casing, a set of revoluble yielding hammers mounted on the shaftadjacent to the inlet, a disk shaped rotor mounted on the shaft betweenthe hammers and the outlet, r'evoluble impact members onthe outlet sideof said rotor, stationary impact members on the casing wall adjacent tosaid revoluble impact members, and a partition wall in the lower part ofthe casing between the hammers and the disk and close to the disk.

11. A pulverizing apparatus comprising a casing having an inlet and anoutlet located centrally thereof, a horizontal shaft rotatably mountedwithin said casing, a set of hammers pivotally mounted on centers spacedfrom the axis of the shaft and arranged to revolve adjacent the inlet, adisk shaped rotor mounted on the shaft so as to form a secondpulverizing zone adjacent the outlet, a partition wall in the lower partof the casing between the hammers and the disk and close to the disk,revoluble impact members on the rotor in the second zone, stationaryimpact members on the casing wall in the second zone, and a rejectordevice to prevent the passage of coarse material through said outlet.

Signed at \Vorcester, Mass, this 8th day of April, 1927.

FRED H. DANIELS.

